certain varieties of horsetail can be contained in containers, ive done this for 3+yrs & so do many nurserys
they thrive in damp soil but not impossible to prevent from spreading nor is comfrey impossible to kill
they thrive in damp soil but not impossible to prevent from spreading nor is comfrey impossible to kill
same has been said about modern agriculture hence the rise/shift to eco-agriculture & ecological designThey ruin ecosystems, reduce biodiversity and dont support many native insects.